JBossWSBusFactory has a check on Spring availability to decide the type of CXF BusFactory to build (Spring or not). The check is on TCCL being able to load Spring classes, but that's not enough in a JBoss Modules environment. As a matter of fact, that check needs to be extended to the defining classloader of the JBossWSBusFactory (which is the classloader for the org.jboss.ws.jaxws-client module), to be sure the factory can actually be loaded (it's going to be loaded using the defining classloader and of course the CXFBusFactory imports Spring classes)